Have you already registered your iPhone 7/app while on the same Wifi network as your genie? If so, and you get this while outside your home, this is a known issue (still happening to me). If you are getting this while trying to register your device while on the same Wifi network, then this is also apparently a known issue with some versions of the Genie software. It happened to me and resolved once I got another genie software update.
(So now I can watch all channels on my phone while on home Wifi, and I can pretty much watch all channels except locals and my DVR when I’m outside the home.)
I had the same issue with the app. I did an online chat and they re-synced the genie on their end and then I was able to connect. however, I still can't get it to find the genie on the network. glad it's a known issue as mentioned above.